The powered roller conveyors with which I am familiar provide a means for simultaneously rotating all of the rollers. If the conveyors is of substantial length, such as 100 or 200 feet, it takes a large motor to simultaneously rotate all of the rollers under load. Further, in the accumulation mode, there are high pressures between loads. Such simultaneous rotation of all of the rollers may be accomplished by driving a belt in frictional contact with the rollers with the top run of the belt moving in a direction opposite to the direction of movement of the load and include load responsive sensors as per the conveyors in U.S. Pat. Nos. 3,612,248 and 3,770,102 if reduction accumulation pressure is desired.
Another type of powered roller conveyor provides a pad on the belt so that only some of the rollers are driven at any given time. Since the belt top run is moving in a direction opposite to the direction of the load, the load moves intermittently with a jerky movement. Since the rollers adjacent the discharge end of the conveyor are the first ones to be rotatably driven by the frictional contact with a pad on the belt, there may be a substantial time lag before a load at the inlet end of the roller conveyor begins moving.
The present invention is directed to a powered roller conveyor for transportion or accumulation which may utilize a substantially smaller drive motor for rotatably driving a discrete number of rollers substantially smaller in number than the total number of rollers while at the same time providing a conveyor which continuously moves the load in the desired direction, and substantially reduces accumulation pressure without the use of sensors.